Ylide-Substituted Phosphines: A Platform of Strong Donor Ligands for Gold Catalysis and Palladium-Catalyzed Coupling Reactions

On the ambiphilic character of phosphanylidenephosphoranes and manipulation of phosphinidenoid reactivity with Lewis acids

“…215−217 pm (6:R-9:R) compared to the free phosphanylidene-phosphoranes (cf. [19] 4(3) pm). [34] Attempts to synthesize and/or crystallize the corresponding GaI3 species 7:R (R = Mes Ter, Dip Ter) failed due to considerable decomposition of the respective phospha-Wittig reagent.…”

“…The reaction of carbonyl compounds with such ylides then chemoselectively yields alkenes under concomitant formation of phosphineoxides which drives these reactions. The principles of the Wittig reactions have been adapted and the ylidic carbon atom has been further modified [4] or has been replaced by heteroatoms. An impressive portfolio of Wittig-type reactions has been published to date and the field is still evolving.…”

“…The replacement of the CR2 fragment in the conventional Wittig reagent R3P (+) -C (-) R2 with an isolobal phosphinidene fragment, P−R, yields so called phospha-Wittig reagents of the type R−P (-) -P (+) R'3. [15] These systems can be best described as phosphanylidene-σ 4 -phosphoranes or as phosphine-stabilized (coordinated) phosphinidenes. [15] Since the first reports by Burg and Mahler in the 1960s, [16,17] a number of stable, mostly aryl-substituted or acenaphtene-based, metal-free phosphanylidene-σ 4 -phosphoranes have been reported.…”

“…[15] These systems can be best described as phosphanylidene-σ 4 -phosphoranes or as phosphine-stabilized (coordinated) phosphinidenes. [15] Since the first reports by Burg and Mahler in the 1960s, [16,17] a number of stable, mostly aryl-substituted or acenaphtene-based, metal-free phosphanylidene-σ 4 -phosphoranes have been reported. [8,[18][19][20][21][22][23] Aryl-substituted variants have been first described by Protasiewicz and co-workers and it was shown that these systems cleanly react with aldehydes to generate phosphaalkenes akin to the formation of alkenes in the classical Wittig reaction.…”

Modulating the reactivity of phosphanylidenephosphoranes towards water with Lewis acids

“…The reaction of carbonyl compounds with such ylides then chemoselectively yields alkenes under the concomitant formation of phosphine oxides which drives these reactions. The principles of the Wittig reaction have been adapted and the ylidic carbon atom has been further modified, 4 or has been replaced by heteroatoms. An impressive portfolio of Wittig-type reactions has been published to date and the field is still evolving.…”